Brunelleschi's Dome

Brunelleschi's Dome is one of those feats of engineering that still feels slightly impossible. When Filippo Brunelleschi won the commission in 1420, nobody — including him, arguably — knew exactly how to span a 42-meter opening without traditional wooden centering. He invented a self-supporting herringbone brick pattern, built two nested shells for structural strength, and essentially created construction techniques that engineers still study today. The dome was completed in 1436 and remains the largest masonry dome ever built. The climb is 463 steps with no elevator — a narrow, winding stone staircase that takes you between the two shells of the dome. Partway up, you emerge onto an interior gallery directly beneath the massive Last Judgment fresco by Vasari and Zuccari. The scale of the painting is staggering when you're right next to it rather than looking up from 55 meters below. The final push takes you to the outdoor terrace at the lantern, where you get a 360-degree panorama of Florence and the Tuscan hills that is genuinely one of the best views in Italy. Book your time slot well in advance — this is the most in-demand ticket in the Duomo complex and sells out days ahead in peak season. The climb is not suitable for anyone with claustrophobia or mobility issues.